Initial prune image support in wslc service

[yao-msft]

Summary of the Pull Request

Initial prune image support in wslc service

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

Added tests.

[Copilot]

Pull request overview

This PR adds initial “image prune” support to the WSLC session API by plumbing a new COM method through WSLCSession into the Docker Engine /images/prune endpoint, and validating the behavior with new Windows tests.

Changes:

• Adds IWSLCSession::PruneImages along with new IDL types/options/results for image pruning.
• Implements image prune in WSLCSession and DockerHTTPClient, including Docker schema support for prune responses.
• Adds a new ImagePrune test and a small RAII helper for freeing prune results.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/windows/WSLCTests.cpp	Adds ImagePrune test coverage for prune behavior and error paths.
src/windows/wslcsession/WSLCSession.h	Declares the new PruneImages COM method on WSLCSession.
src/windows/wslcsession/WSLCSession.cpp	Implements WSLCSession::PruneImages, including filter translation and result marshaling.
src/windows/wslcsession/DockerHTTPClient.h	Adds prune filter struct and PruneImages method declaration.
src/windows/wslcsession/DockerHTTPClient.cpp	Implements POST /images/prune request with Docker filters query param.
src/windows/service/inc/wslc.idl	Introduces prune-related structs/enums and adds PruneImages to IWSLCSession.
src/windows/inc/docker_schema.h	Adds PruneImageResult schema used to parse Docker prune responses.
src/windows/common/wslutil.h	Adds ImagePruneResult RAII wrapper for WSLCPruneImagesResults.

Comments suppressed due to low confidence (1)

src/windows/service/inc/wslc.idl:660

• Adding a new method to the existing COM interface IWSLCSession changes the vtable layout for all subsequent methods (e.g., CreateContainer and later), which is a binary-breaking change for any existing clients built against the previous IDL. To preserve COM ABI compatibility, add a new interface (e.g., IWSLCSession2 with a new IID) that extends IWSLCSession, and implement/query that from the session object instead of inserting methods into IWSLCSession.

    // Image management.
    HRESULT PullImage([in] LPCSTR Image, [in, unique] LPCSTR RegistryAuthenticationInformation, [in, unique] IProgressCallback* ProgressCallback);
    HRESULT BuildImage([in] const WSLCBuildImageOptions* Options, [in, unique] IProgressCallback* ProgressCallback, [in, unique, system_handle(sh_event)] HANDLE CancelEvent);
    HRESULT LoadImage([in] WSLCHandle ImageHandle, [in, unique] IProgressCallback* ProgressCallback, [in] ULONGLONG ContentLength);
    HRESULT ImportImage([in] WSLCHandle ImageHandle, [in] LPCSTR ImageName, [in, unique] IProgressCallback* ProgressCallback, [in] ULONGLONG ContentLength);
    HRESULT SaveImage([in] WSLCHandle OutputHandle, [in] LPCSTR ImageNameOrID, [in, unique] IProgressCallback * ProgressCallback, [in, unique, system_handle(sh_event)] HANDLE CancelEvent);
    HRESULT ListImages([in, unique] const WSLCListImageOptions* Options, [out, size_is(, *Count)] WSLCImageInformation** Images, [out] ULONG* Count);
    HRESULT DeleteImage([in] const WSLCDeleteImageOptions* Options, [out, size_is(, *Count)] WSLCDeletedImageInformation** DeletedImages, [out] ULONG* Count);
    HRESULT TagImage([in] const WSLCTagImageOptions* Options);
    HRESULT InspectImage([in] LPCSTR ImageNameOrId, [out] LPSTR* Output);
    HRESULT PruneImages([in, unique] const WSLCPruneImagesOptions* Options, [out] WSLCPruneImagesResults* Result);

    // Container management.
    HRESULT CreateContainer([in] const WSLCContainerOptions* Options, [out] IWSLCContainer** Container);
    HRESULT OpenContainer([in, ref] LPCSTR Id, [out] IWSLCContainer** Container);
    HRESULT ListContainers([out, size_is(, *Count)] WSLCContainerEntry** Containers,
                                            [out] ULONG* Count,
                                            [out, size_is(, *PortsCount)] WSLCContainerPortMapping** Ports,
                                            [out] ULONG* PortsCount);
    HRESULT PruneContainers([in, unique, size_is(FiltersCount)] WSLCContainerPruneFilter* Filters, [in] DWORD FiltersCount, [in] ULONGLONG Until, [out] WSLCPruneContainersResults* Result);

[OneBlue]

Change looks good, minor comments

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

[Copilot]

PruneImages validates dangling flags and unknown bits, but it doesn't validate the Labels pointer/count relationship. If Options->LabelsCount > 0 while Options->Labels is nullptr, the call currently succeeds and silently ignores the requested filters. Please add an argument check (similar to ListImages) to reject this case (e.g., return E_INVALIDARG when LabelsCount > 0 && Labels == nullptr).

Suggested change

	RETURN_HR_IF(E_INVALIDARG, WI_IsAnyFlagSet(static_cast<WSLCPruneImagesFlags>(Options->Flags), ~WSLCPruneImagesFlagsValid));
	RETURN_HR_IF(E_INVALIDARG, WI_IsAnyFlagSet(static_cast<WSLCPruneImagesFlags>(Options->Flags), ~WSLCPruneImagesFlagsValid));
	RETURN_HR_IF(E_INVALIDARG, Options->LabelsCount > 0 && Options->Labels == nullptr);